1. Field of the Invention
The present invention relates generally to heating and cooling systems, and particularly to a heat exchanger in cooling systems to save energy in cooling operations, such as during peak utility use periods.
2. Description of the Related Art
The need to produce heated or cooled air or other fluid, and/or to transfer warmer or cooler air or other fluid from one location to another, has been evident for some time. Contemporary means for cooling the interior of a structure is by air conditioning, essentially comprising a fluid refrigerant that changes phase from liquid to gas depending upon its temperature and pressure. A compressor is used to drive the refrigerant through the system, with expansion of the fluid from liquid to gas resulting in a decrease in temperature that is transferred to the area being cooled. More generally, such systems are known as “heat pumps,” and are reversible to deliver warmer air into the structure when desired.
All of these systems require energy input, as their compressors are generally relatively high power demand devices. They are generally powered by electrical power from the local electrical grid or network. Electrical power companies have long recognized that electrical demand is greatest at certain times of the day, depending upon the season and ambient temperature. In warmer conditions, electrical demand is of course highest during the warmest part of the day, with demand decreasing as the temperature cools. Accordingly, electrical power companies generally increase the cost of electricity to the consumer during the periods of greatest demand, both to encourage conservative use during those periods in order to encourage reducing the need for more power production, for example.
A number of devices have been developed in response to the above-described electrical rate adjustment system, with such devices universally operating during off-peak times and storing the resulting cold mass (e.g., water, etc.) to cool the desired area during periods of higher energy cost, typically during the warmer part of the day. These devices generally operate at a sufficiently low temperature as to produce ice buildup on the water contact surface of the interface between the cooling agent and the water being cooled. Ice production is desirable, as the colder temperature of the ice is capable of absorbing more heat from the volume being cooled. However, it can be difficult to remove ice from the freezing surface (e.g., cooling coils, etc.), which ice removal process requires energy over and above the energy required for cooling. Also, many such systems produce ice in relatively large volumetric units (e.g., ice cubes or blocks, etc.), with the relatively high volume to surface area ratio of such ice reducing the ability of the ice to melt rapidly to absorb heat from the water.
An example of a device to remove ice from a surface is found in Japanese Patent Publication No. 3-204577 published on Sep. 16, 1991 to Daikin Industries, Ltd. This reference describes a hollow cylindrical container adapted to form ice upon its inner surface. A concentric shaft rotates within the cylinder, with elongate scraper blades extending radially from the shaft to bear against the inner wall of the cylinder. The blades are stiffened by a metal insert to limit distortion.
An example of a cooling system that produces water ice for use in cooling the water in the system is found in Japanese Patent No. 2000-304307 published on Nov. 2, 2000 to Tohoku Electric Power Co. et al. This reference describes a cooling system having several tanks, with ice being formed in one tank and then transferred to another tank for melting and cooling water within that tank.
Thus, a heat exchanger addressing the aforementioned problems is desired.